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(No Model.)

k R. G. WINSLOW.

ART OF MANUFACTURING MATES.

No. 262,528 Patented Aug. 8, 18 82.

UNITED STATES PATENT OEEicE.

ROBERT G. WINSLOW, OF CHICAGO, ILLINOIS, ASSIGNOR OF ONE-HALF TO OLIVERW. BARRETT, OF SAME PLACE.

ART OF MANUFACTURING SLATES.

SPECIFICATION forming part of Letters Patent No. 262,528, dated August8, 1882.

Application filed J l ne 17, 1882. (No model.)

To all 'wlwm 2t may concern:

Be it known that I, ROBERT Gr. \VINSLOW, of Chicago, in the county ofCook and State of Illinois, have invented certain new and use- 5 fulImprovements in the Art of Manufacturing Slates, of which the followingis a description that will enable others to make and use thesame,reference being bad to the accompanying drawings, and to letters ofreference marked thereon, forming a part of this specification.

This invention relates to an improvement in the manufacture of slates,as will be hereinafter fully set forth.

Figure l is a face view of a slate embodying my improvement. Fig. 2 is atransverse section in the plane 2 2, Fig. 1; and Fig. 3, a modification.

Referring to the drawings, A represents the slate proper, and B theframe.

In manufacturing the slate I first take a sheet, 0, of common straw orcard board of suitable thickness to form a substantial body. Each sideof this central body, 0, is then covered with the leavesD D,whicharecomposed of smoothly-finished press-board. Thejoining surfaces areunited by the use of any suitable adhesive composition, while the outeror writing surface of the leaves D D is covered with 0 acomposition,hereinafter set forth, which renders the surface smooth andhard, and readily admits of the writing or figures being erased. Thecorner-jointsof theframe are strengthened and protected by means of thetriangular caps 5 a, which are composed of some noiseless material, likeleather.

The slate-frame may be constructed of thick card-hoard in place of woodif suchachangeis found to be desirable, and when the corners arefirmlyjoined together by any suitable adhesive composition thetriangular corner caps or protectors may be dispensed with. This form ofconstruction produces an article that is cheap, light, durable, andnoiseless, possess- 5 ing all the advantages of the ordinary slate andnone of the objectionable features.

The modification illustrated in Fig. 3 of the drawings shows a tabletconsisting of a number of leaves provided with covers and made up inbook form. These leaves are finished with the composition in the samemanner and by the same process employed in the manufacture of theslates.

The process and composition used in the preparation of thewriting-surface are as follows: 5 For black slates I first take one pintof silicate and one pint of bone-black to one and one-half pint ofwater, mixing the same thoroughly, and then running it through agrinding-mill. This mixture is then applied to theoutside sur- 6o faceof the press-board by means of a soft brush. Each sheet of board shouldhave two or three coats of this mixture, and should be sandpapered aftereach application. The writing-surface is finally finished by beingvarnished with a composition of gutta-percha and carbon, equal parts, towhich are added three parts water and one part liquid silicate. Thisfinishing composition should be first filtered before being used.

In preparing whitewriting-surfaces the bone black should be omitted; orany colored slatc may be produced by simply using paper or press boardof the desired color.

Having thus described my invention, what I 7 claim as new, and desire tosecure by Letters Patent, is-

1. An improved process in the manufacture of slates, which consists ofapplying to the surface of press-board or other suitable mate- 8c rialacomposition of silicate, bone-black, and water in the proportionsgiven, one or more coats being applied to form the writing-surface,which is sandpapered after the application of each coat, and finallyfinished by being varnished with a composition consisting ofgutta-percha, carbon, and liquid silicate, equal parts, and water threeparts, substantially as set forth.

2. As a new article of manufacture, a slate or writing-tablet preparedby the process herein described.

ROBERT G. WINSLOVV.

Witnesses:

L. M. FREEMAN, L. B. COUPLAND.

